A field-of-view controlling arrangement for a display screen or window includes overlay in the form of a single sheet of light transmitting material having a plurality of parallel, spaced apart v-shaped grooves, or a plurality of polyhedral, conical, or frustoconical lens or prism structures, that serve...http://www.google.com/patents/US20020163728?utm_source=gb-gplus-sharePatent US20020163728 - Optical sheets or overlays

A field-of-view controlling arrangement for a display screen or window includes overlay in the form of a single sheet of light transmitting material having a plurality of parallel, spaced apart v-shaped grooves, or a plurality of polyhedral, conical, or frustoconical lens or prism structures, that serve to shift or expand the field-or-view of an image or scene viewed through the sheet. Any of the angled or curved surfaces of the resulting lens or prism structures may be treated to attenuate or scatter light, thereby providing a privacy screening effect with respect to a range of angles determined by the orientation of the treated surfaces.

Images(14)

Claims(43)

What is claimed is:

1. An overlay, comprising:

a single light-transmitting sheet including a plurality of parallel grooves defined by sets of intersecting angled surfaces,

wherein the grooves are spaced apart from each other.

2. An overlay as claimed in claim 1, wherein at least one of said sets of angled surfaces is arranged to attenuate light transmitted through the overlay.

3. An overlay as claimed in claim 2, wherein two of said sets of angled surfaces are arranged to attenuate light transmitted through the overlay.

4. An overlay, comprising a single light-transmitting sheet including a plurality of polyhedral structures.

6. An overlay as claimed in claim 4, wherein said polyhedral structures are truncated tetrahedral structures arranged in a grid pattern.

7. An overlay as claimed in claim 4, wherein said polyhedral structures are tetrahedral structures arranged in staggered rows.

8. An overlay as claimed in claim 4, wherein said polyhedral structures are tetrahedral structures arranged in a grid pattern.

9. An overlay as claimed in claim 4, wherein said polyhedral structures are truncated hexahedral structures arranged in a honeycomb pattern.

10. An overlay as claimed in claim 4, wherein said polyhedral structures are truncated hexahedral structures arranged in a honeycomb pattern.

11. An overlay as claimed in claim 4, wherein said polyhedral structures are hexahedral structures arranged in a honeycomb pattern.

12. An overlay as claimed in claim 4, wherein selected surfaces of said polyhedral structures are treated by processes selected from the group consisting of coating processes, delustering, chemical or laser etching, casting, and differential polishing of previously roughened surfaces, to attenuate light passing through the selected surfaces and thereby form a privacy screen.

13. An overlay, comprising a single light-transmitting sheet including a plurality of frustoconical structures.

14. An overlay as claimed in claim 13, wherein curved surfaces of said frustoconical structures are treated by processes selected from the group consisting of coating processes, delustering, chemical or laser etching, casting, and differential polishing of previously roughened surfaces.

15. An overlay, comprising a single light-transmitting sheet including a plurality of conical structures arranged to control a field-of-view for an image or scene viewed through the overlay.

16. An overlay, comprising a single light-transmitting sheet including a plurality of interlocking solids having polygonal bases.

17. An overlay as claimed in claim 16, wherein said polygonal bases are hexagonal, thereby forming a honeycomb pattern.

18. An overlay as claimed in claim 17, wherein said interlocking solids are truncated hexahedra.

19. An overlay as claimed in claim 18, wherein a top surface of each hexahedron is planar.

20. An overlay as claimed in claim 18, wherein a top surface of each hexahedron is lens-shaped.

21. An overlay as claimed in claim 20, wherein side surfaces of each hexahedron are curved.

22. An overlay as claimed in claim 18, wherein side surfaces of each hexahedron are curved.

23. An overlay as claimed in claim 16, wherein said polygonal bases are diamond-shaped.

24. An overlay as claimed in claim 23, wherein said interlocking solids are truncated tetrahedra.

25. An overlay as claimed in claim 24, wherein a top surface of each tetrahedron is planar.

26. An overlay as claimed in claim 24, wherein a top surface of each tetrahedron is lens-shaped.

27. An overlay as claimed in claim 26, wherein side surfaces of each tetrahedron are curved.

28. An overlay as claimed in claim 24, wherein side surfaces of each tetrahedron are curved.

29. A field-of-view controlling arrangement, comprising:

a single light-transmitting sheet arranged to expand or shift portions of a field-of-view for an image or scene viewed through the sheet,

wherein the sheet includes a plurality of parallel grooves defined by sets of intersecting angled surfaces, and

wherein the grooves are spaced apart from each other.

30. A field-of-view controlling arrangement as claimed in claim 29, wherein at least one of said sets of angled surfaces is arranged to attenuate light transmitted through the sheet, thereby forming a privacy screen while maintaining said expanded field-of-view.

31. A field-of-view controlling arrangement as claimed in claim 30, wherein two of said sets of angled surfaces are arranged to attenuate light transmitted through the sheet.

32. A field-of-view controlling arrangement, comprising a single light-transmitting sheet including a plurality of polyhedral structures arranged to expand, shift, or restrict a field-of-view for an image or scene viewed through the sheet.

36. A field-of-view controlling arrangement as claimed in claim 32, wherein said polyhedral structures are tetrahedral structures arranged in a grid pattern.

37. A field-of-view controlling arrangement as claimed in claim 32, wherein said polyhedral structures are truncated hexahedral structures arranged in a honeycomb pattern.

38. A field-of-view controlling arrangement as claimed in claim 32, wherein said polyhedral structures are truncated hexahedral structures arranged in a honeycomb pattern.

39. A field-of-view controlling arrangement as claimed in claim 32, wherein said polyhedral structures are hexahedral structures arranged in a honeycomb pattern.

40. A field-of-view controlling arrangement as claimed in claim 32, wherein selected surfaces of said polyhedral structures are treated by processes selected from the group consisting of coating processes, delustering, chemical or laser etching, casting, and differential polishing of previously roughened surfaces, to attenuate light passing through the selected surfaces and thereby form a privacy screen.

41. A field-of-view controlling arrangement, comprising a single light-transmitting sheet including a plurality of frustoconical structures arranged to expand, shift, or restrict a field-of-view for an image or scene viewed through the sheet.

42. A field-of-view controlling arrangement as claimed in claim 41, wherein curved surfaces of said frustoconical structures are treated by processes selected from the group consisting of coating processes, delustering, chemical or laser etching, casting, and differential polishing of previously roughened surfaces.

43. A field-of-view controlling arrangement, comprising a single light-transmitting sheet including a plurality of conical structures arranged to expand, shift, or restrict a field-of-view for an image or scene viewed through the sheet.

Description

[0001]

This application is a continuation-in-part of copending U.S. patent application Ser. No. 09/846,455, filed May 2, 2001, and incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002]

1. Field of the Invention

[0003]

This invention relates to single-sheet light transmitting sheets or overlays, and to arrangements for using such sheets or overlays.

[0004]

The sheets or overlays may, by way of example, be used to control the field-of-view or range of angles over which an image or scene can be discerned, by either expanding, shifting, and/or screening portions of the image or scene, on any side and in any selected direction.

[0005]

Alternatively, the sheets or overlays may be used collect or capture light, to permit viewing of different images or image portions at different angles relatively to a display screen, to separate or combine images, or to serve as retroreflectors.

[0006]

2. Description of Related Art

[0007]

Field-of-view expansion overlays made up of conventionally-shaped microprism or lenticular sheets having parallel groove or lens structures are disclosed in copending U.S. Pat. No. 09/780,535, while field-of-view restricting (i.e., privacy screening) overlays using the same types of conventionally configured parallel groove or lens structures are disclosed in copending U.S. patent application Ser. No. 09/481,942.

[0008]

The present invention proposes to apply the image expansion or restriction principles described in the copending applications to a variety of novel sheet structures, in which the parallel grooves of the sheet are spaced apart, or are replaced by arrays of structural elements having polyhedral, frustoconical, or conical shapes, and/or that are configured as solids arranged in an interlocking or honeycomb pattern.

[0009]

In particular, the present invention proposes to provide a single-sheet light transmitting overlay for a display screens or windows in which one surface is formed or cast to include the above-mentioned spaced apart parallel grooves or polyhedral, frustoconical, or conical structural elements, and/or solids arranged in an interlocking or honeycomb pattern, so that the structural elements shift or expand the field-of-view of an image viewed through the overlay. Furthermore, by selectively treating any of the surfaces of the structural elements, a field-of-view restriction or screening effect may be achieved without affecting the image shifting or expansion effects of the remaining untreated surfaces.

[0010]

In addition to provide field-of-view controlling the effects, the novel sheet structures of the prevent invention may be used to capture light, for example in solar panels, to separate or combine images, and if provided with a reflective backing, to serve as retroreflectors.

[0011]

By way of background, the following patents are directed to microprism sheets in general, including microprism sheets having treated surfaces and surface treatment methods therefor:

the following patents are directed to use of microprism or lenticular sheets to increase the field of view in non-projection or direct sight type LCD systems:

[0017]

U.S. Pat. Nos. 5,745,199 and 5,555,476, both to Suzuki et al.

[0018]

While these patents disclose a wide variety of uses for microprism or lenticular sheets similar to those disclosed in U.S. patent application Ser. Nos. 09/780,535 and 09/481,942, they do not disclose the particular structural elements shapes of the present invention, or use of such shapes in field-of-view controlling (i.e., expanding, shifting, or restricting) arrangements, image separating or combining arrangements, light collection devices, or as retroreflectors.

SUMMARY OF THE INVENTION

[0019]

It is accordingly a first objective of the invention to provide more versatile single-sheet, light-transmitting overlays that offer enhanced field-of-view control, permitting the field-of-view of an image or scene to be controlled or restricted from any side or combination of sides, over any range of angles, and without substantially increasing the cost or difficulty of manufacture.

[0020]

It is a second objective of the invention to provide field-of-view controlling arrangements utilizing such single-sheet, light-transmitting overlays that provide enhanced field-of-view control.

[0021]

It is a third objective of the invention to provide display screen overlays, for computer monitors, televisions, and the like, that can provide privacy screening or field-of-view expansion from any side of the screen, including both sides, the top, and the bottom, or combinations thereof.

[0022]

It is a fourth objective of the invention to provide privacy screens that may be applied to a window, and which not only serve as a blind, but also may be arranged to improve the view through the window, and/or to replace an undesired view with images or graphics.

[0023]

It is a fifth objective of the invention to provide novel sheet structures that not only can be used for field-of-view control, but that may also be advantageously adapted for use in image separating or combining devices, light collectors, and as retroreflectors.

[0024]

These objectives are achieved, in accordance with the principles of various preferred embodiments of the invention, by providing an overlay in the form of a single sheet of light transmitting material having a plurality of parallel, spaced apart v-shaped grooves, or a plurality of polyhedral, conical, or frustoconical lens structures, and/or solid (i.e., three-dimensional) lens structures arranged in an interlocking or honeycomb pattern, and that serve to shift or expand the field-or-view of an image or scene viewed through the sheet, that direct incident light in a desired manner, or that have the effect of combining or separating images, depending on the viewing angle.

[0025]

In each of the embodiments of the invention, any angled or curved surface may be treated to attenuate or scatter light, thereby providing a privacy screening effect with respect to a range of angles determined by the orientation of the surfaces. The surface treatments applied may consist of any surface treatments that have the effect of absorbing or scattering light and that can be applied to selected surfaces by means of a mask, control of the surface treatment tool, or use of an appropriate die, including application of opaque, light diffusing, or polarizing coatings, delustering, chemical or laser etching, casting, and differential polishing of previously roughened surfaces, as well as any other surface treatment methods described in the above-cited patents or patent applications, or that are known or may become known to those skilled in the art.

[0026]

In the case of polarizing coatings, a privacy screening effect can be obtained by providing a polarizing coating on an entire back surface of the overlay, and by oppositely polarizing selected surfaces on the front side of the overlay.

[0027]

In addition to or instead of including light attenuating or light scattering coatings, the overlays of the invention may be provided with non-directional treatments such as reflective coatings (useful in forming retroreflectors), radiation shielding coatings, or embedded images or graphics.

[0028]

Furthermore, the extremely versatile overlays of the invention may be arranged to facilitate light collection by directing light incident light from a relatively wide field of view into a light guide (which is especially useful for solar collectors), or the overlays may be provided with polarizing or other coatings that facilitate image combination or separation.

[0029]

When arranged to provide field-of-view control, i.e., as privacy screens, the overlays of the preferred embodiments of the invention are especially suitable for use in restricting or facilitating viewing by persons situated above or below, or to the side of, a computer monitor or television screen. However, the field-of-view controlling overlays may be used in any of a variety of potential applications that might involve restricted or enhanced viewing of an image or scene, including applications in which the overlays of the invention are applied to windows to serve as blinds.

[0030]

When applied to a window, the privacy screens of the invention not only can provide privacy and restrict incoming light, but also can modify the view through the window by using the prisms or lenticular structures of the overlay to bend light is selected directions, or modify the view by adding images or graphics visible at selected angles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]

[0031]FIG. 1 is a perspective view of one of the preferred field-of-view controlling sheets used as a computer display screen overlay.

[0032]

[0032]FIG. 2 is a perspective view of a preferred embodiment of the field-of-view controlling overlay of FIG. 1, in which the single sheet that makes up the overlay includes parallel, spaced apart grooves.

[0033]

[0033]FIG. 3 is a perspective view of a portion of a single sheet field-of-view controlling overlay including truncated tetrahedral structures arranged in staggered rows according to the principles of a second preferred embodiment of the invention.

[0034]

[0034]FIG. 4 is a perspective view of a portion of a single sheet field-of-view controlling overlay including truncated tetrahedral structures arranged in a grid pattern according to the principles of a third preferred embodiment of the invention.

[0035]

[0035]FIG. 5 is a perspective view of a portion of a single sheet field-of-view controlling overlay including tetrahedral structures arranged in staggered rows according to the principles of a fourth preferred embodiment of the invention.

[0036]

[0036]FIG. 6 is a perspective view of a portion of a single sheet field-of-view controlling overlay including truncated tetrahedral structures arranged in a grid pattern according to the principles of a fifth preferred embodiment of the invention.

[0037]

[0037]FIG. 7 is a perspective view of a portion of a single sheet field-of-view controlling overlay including truncated hexahedral structures arranged in a honeycomb pattern according to the principles of a sixth preferred embodiment of the invention.

[0038]

[0038]FIG. 8 is a perspective view of a portion of a single sheet field-of-view controlling overlay including tetrahedral structures arranged in a honeycomb pattern according to the principles of a seventh preferred embodiment of the invention.

[0039]

[0039]FIG. 9 is a plan view of the overlay of FIG. 3, in which no surfaces are treated to provide a privacy screening effect.

[0040]

FIGS. 10-13 are plan views of the overlay of FIG. 3, in which different surfaces are treated to control the viewing angle in different directions.

[0041]

[0041]FIG. 14 is a plan view of the overlay of FIG. 4, in which no surfaces are treated to provide a privacy screening effect.

[0042]

FIGS. 15-18 are plan views of the overlay of FIG. 4, in which different surfaces are treated to control the viewing angle in different directions.

[0043]

[0043]FIG. 19 is a plan view of the overlay of FIG. 5, in which no surfaces are treated to provide a privacy screening effect.

[0044]

FIGS. 20-23 are plan views of the overlay of FIG. 5, in which different surfaces are treated to control the viewing angle in different directions.

[0045]

[0045]FIG. 24 is a plan view of the overlay of FIG. 6, in which no surfaces are treated to provide a privacy screening effect.

[0046]

FIGS. 25-28 are plan views of the overlay of FIG. 6, in which different surfaces are treated to control the viewing angle in different directions.

[0047]

[0047]FIG. 29 is a plan view of the overlay of FIG. 7, in which no surfaces are treated to provide a privacy screening effect.

[0048]

FIGS. 30-39 are plan views of the overlay of FIG. 7, in which different surfaces are treated to control the viewing angle in different directions.

[0049]

[0049]FIG. 40 is a plan view of the overlay of FIG. 8, in which no surfaces are treated to provide a privacy screening effect.

[0050]

FIGS. 41-50 are plan views of the overlay of FIG. 8, in which different surfaces are treated to control the viewing angle in different directions.

[0051]

[0051]FIG. 51 is a perspective view of a portion of a single sheet field-of-view controlling overlay including frustoconical structures according to the principles of an eighth preferred embodiment of the invention.

[0052]

[0052]FIG. 52 is a plan view of the overlay of FIG. 51, in which one surface is treated to control the viewing angle in different directions.

[0053]

[0053]FIG. 53 is a plan view of the overlay of FIG. 51, in which no surface is treated to provide a privacy screening effect.

[0054]

[0054]FIG. 54 is a perspective view of a portion of a single sheet field-of-view controlling overlay including conical structures in accordance with the principles of a ninth preferred embodiment of the invention.

[0055]

FIGS. 55-57 are respective side, plan, and isometric views of a single sheet field-of-view controlling overlay including an interlocking or honeycomb arrangement of tetrahedral solids arranged to include a lens surface in accordance with the principles of a tenth preferred embodiment of the invention.

[0056]

FIGS. 58-60 are respective side, plan, and isometric views of a single sheet field-of-view controlling overlay including an interlocking or honeycomb arrangement of tetrahedral solids arranged to include lens-shaped side surfaces in accordance with the principles of an eleventh preferred embodiment of the invention.

[0057]

FIGS. 61-63 are respective side, plan, and isometric views of a single sheet field-of-view controlling overlay including an interlocking or honeycomb arrangement of lens-shaped solids in accordance with the principles of a twelfth preferred embodiment of the invention.

[0058]

FIGS. 64-66 are respective side, plan, and isometric views of a single sheet field-of-view controlling overlay including an interlocking arrangement of truncated non-regular pyramidal structures in accordance with the principles of a thirteenth embodiment of the invention.

[0059]

FIGS. 67-69 are respective side, plan, and isometric views of a single sheet field-of-view controlling overlay including an interlocking arrangement of non-regular pyramidal solids arranged to include a lens surface in accordance with the principles of a fourteenth preferred embodiment of the invention.

[0060]

FIGS. 70-72 are respective side, plan, and isometric views of a single sheet field-of-view controlling overlay including an interlocking arrangement of non-regular pyramidal solids arranged to include lens-shaped side surfaces in accordance with the principles of an fifteenth preferred embodiment of the invention.

[0061]

FIGS. 73-75 are respective side, plan, and isometric views of a single sheet field-of-view controlling overlay including an interlocking arrangement of lens-shaped solids in accordance with the principles of a sixteenth preferred embodiment of the invention.

[0062]

[0062]FIGS. 76 and 77 are plan views of a single sheet field-of-view controlling overlay including a honeycomb pattern of lens-shaped solids in accordance with the principles of respective seventeenth and eighteenth preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063]

[0063]FIG. 1 illustrates one application of the embodiments illustrated in FIGS. 2-50. In this embodiment, an overlay 1 designed to be used with the display screen 2 of a computer, to either expand, shift, or restrict the field-of-view in any desired direction or directions, or to separate or combine images. For example, using the embodiment of FIG. 2, the field-of-view could be restricted in order to prevent eavesdroppers from viewing the screen from the left or right sides, but expanded to permit viewing of the screen from above. Alternatively, using the embodiment of FIGS. 3-77, the field-of-view could be expanded or restricted on any number of sides, or on any combination of multiple sides, or the overlay could be arranged such that different images or portions of an image may be viewed through different facets.

[0064]

Alternatively, the sheets or overlays illustrated in FIGS. 2-77 could be arranged to collect light. This is especially useful in solar panels, since the same principles that permit expansion of the field-of-view can be applied to increasing the efficiency of solar light collection, with the goal of directing the light to a light guide that guides the light to a photo-electric panel, water heater, or other energy conversion device.

[0065]

If the sheets are provided with a reflecting coating on the surface opposite the lenses or prisms, or on the surfaces of the lenses or prisms, a retroreflective effect can be obtained, in which light incident on the sheet is reflected in a particular direction. Overlays or sheets arranged in this manner are especially suitable for use in projection screens, but may also be useful on road signs, nighttime wearing apparel, reflectors for bicycles or other vehicles, and in any other application in which retroreflectivity is utilized.

[0066]

Turning to the specific structures which make up the invention, FIG. 2 shows a first preferred embodiment of the invention arranged to provide modification for any two opposite sides of field-of-view. This embodiment consists of a sheet 3 having parallel, spaced apart v-shaped grooves formed by angled surfaces 4 and 5. The presence of angled surfaces 4 and 5 has the effect of expanding the field-of-view for an image or scene viewed through the sheet 3. The surfaces 6 connecting the grooves are planar, although it is possible to modify surfaces 6 to having a curvature in order to obtain lensing effects.

[0067]

As in all of the embodiments of the present invention, in order to restrict or screen a portion of the field of view, it is simply necessary to treat at least one of the angled surfaces 4,5 to attenuate or scatter light passing through the treated surfaces. If just one surface is treated, then the field-of-view expansion effect of the other surface will still be maintained, although it is also possible to treat both surfaces, or portions of the surfaces for a two-sided privacy screening effect.

[0068]

The surface treatments applied in this and other embodiments of the invention may consist of any surface treatments that have the effect of absorbing or scattering light and that can be applied to selective surfaces by means of a mask, die, tool, or the like. In addition to coatings, possible surface treatments include delustering, chemical or laser etching, casting, and differential polishing of previously roughened surfaces, as well as any other surface treatment methods described in the above-cited patents or patent applications, or that are known or may become known to those skilled in the art. For example, if the surfaces are treated by printing, graphic images may be added so that the blocked image or scene is replaced by a graphic image.

[0069]

It will of course be appreciated that the surfaces that are not “treated” to scatter or attenuate light in order to create a privacy screening effect may nevertheless be treated to enhance transmission of light through the surfaces, for example by polishing, curing, adding transparent protective coatings, and or printing of portions of the surfaces so as to superimpose graphic images on the images being viewed through the screen. The term “untreated” is intended to mean “not altered to diffuse or attenuate light.”

[0070]

Furthermore, it will be appreciated that a privacy screening effect can be obtained not only by light scattering or attenuation, but also by polarization. In order to obtain privacy screening by polarization, a back surface of the overlay is polarized in a first direction, and then selected facets or surfaces on the front side of the overlay are polarized in the opposite direction so that the oppositely polarized facets or surfaces effectively prevent transmission of light through the surfaces. Furthermore, if the light source itself is polarized, as is the case with a liquid crystal display, privacy screening could be achieved without polarizing the back side of the overlay, so long as the selected facets or surfaces are polarized in a direction opposite the direction of polarization of the display.

[0071]

In addition to treatments that scatter, attenuate, or polarize light in order to provide a privacy screening effect, surface treatments may include anti-radiation coatings, polarizing coatings for purposes other than privacy screening, printing, and other surface treatments such as the above mentioned reflective coating, applied either to one or more facets of the prism structures, but possibly also to the opposite side of the sheet.

[0072]

According to the preferred embodiment of the invention illustrated in FIGS. 3 and 9-13, the field-of-view controlling arrangement is made up of a sheet that include staggered rows of lenticular elements in the form of truncated tetrahedral structures 100 having five sets of mutually parallel surfaces indicated by reference numerals 101-105. According to the principles of this embodiment of the invention, the sheet may be used without treatment of any of the surfaces, in which case the field-of-view is increased on four sides, or any one or more of surfaces 101-105 may be selectively treated to provide a privacy screening effects, the range of angles of which is determined by the orientations of the treated surfaces. For example, in the arrangement of FIG. 9, none of the surfaces are treated, while in the arrangement of FIG. 10, only surface 101 is treated, and in the arrangements of FIGS. 11-13, surfaces 101 and 105; 101, 104, and 105; and 101 and 104 are respectively subjected to a light-attenuating or other surface treatment in the manner described above.

[0073]

[0073]FIGS. 4 and 14-18 illustrate a field-of-view controlling arrangement similar to that of FIGS. 14-18 except that the truncated tetrahedral lenticular elements 200 are arranged in a grid rather than in staggered rows. Again, any or none of the surfaces 201-205 may be subjected to a light-attenuating or other surface treatment in the manner described above.

[0074]

[0074]FIGS. 5 and 19-23 illustrate further embodiments of the invention in which the field-of-view controlling elements are non-truncated tetrahedral structures (300,400) in staggered rows (FIGS. 5 and 19-23) or non-staggered rows (FIGS. 6 and 25-28) and in which any set of surfaces 301-304, 401-404 may be subjected to a light attenuating or other surface treatment, while FIGS. 7, 30-39, 8, and. 40-50 show corresponding arrangements of truncated or non-truncated hexahedral structures 500,600 forming a honeycomb pattern and in which any of surfaces 501-507,601-606 may be treated to create a privacy screening effect, or otherwise treated to facilitate any of the other effects noted above.

[0075]

FIGS. 51-53 show preferred embodiments of the invention in which the field-of-view controlling elements are frustoconical-shaped structures 700 having surfaces 701 and 702 in which the curved surface 701 which forms sides of the structure may optionally be provided with a light-attenuating surface treatment to provide a 360° privacy screening effect as shown in FIG. 52, or with other surface treatments as noted above.

[0076]

Finally, FIG. 54 shows a preferred embodiment of the invention in which the field-of-view controlling elements are conical structures 800 having surfaces 801. This embodiment is primarily for field-of-view expansion since it would be very difficult to selectively treat portions of the conical surfaces in such a way as to still permit viewing of an image through the overlay, although non-selective treatments may of course be applied to either side of the sheet or overlay.

[0077]

One advantage of using interlocking solids that form staggered rows or a honeycomb pattern of field-of-view controlling elements is that the staggering or honeycomb pattern reduces the so-called “staircase” effect, which results in distortion or blurring of non-horizontal or vertical lines, caused by the quantum or discrete nature of aligned microprism or lenticular elements. In addition, non-truncated discrete elements have the advantage of providing maximal glare reduction and expansion of the field-of-view in non-restricted directions.

[0078]

Further examples of arrangements utilizing interlocking or honeycomb patterns are found in FIGS. 55-80. The arrangements of FIGS. 55-63 are similar to those of FIGS. 29-39 except that the truncated hexahedral solids depicted in FIGS. 29-39 are modified to include lens elements 900 (FIGS. 55-57), curved side surfaces 901 (FIGS. 58-60) , or both (FIGS. 61-63) In the arrangements of FIGS. 64-78, the interlocking solids are truncated non-regular tetrahedra, i.e., tetrahedra with a diamond-shaped rather than square base, having either a flat top surface 902 (FIGS. 64-66, a lens-shaped top surface 903 (FIGS. 67-69), lens-shaped side surfaces 904 (FIGS. 70-72), or both (FIGS. 73-75). Finally, as illustrated in FIGS. 76 and 77, the interlocking solids may include more complex shapes, such as the multi-faceted structures shown in FIG. 76, in which the two traverse vertical cross-sections have three and four respective sides extending from the plane of the sheet, or the more continuously curved honeycomb arrangement of FIG. 77, which includes an semi-annular mid-portion and conical end portions.

[0079]

As indicated above, the single sheet field-of-view controlling overlays of the invention may be used as overlays for video displays, for example to restrict eavesdropping with respect to a computer display. In addition, the overlays of the invention may be used as privacy screening window coverings in order to achieve a variety of effects not possible with conventional mechanical blinds. For example, the prisms or lenticular structures that make up the overlays may be used to bend incoming light and improve the view from the window and, if the view from the window does not include any scenes worth expanding, the entire view may be replaced by images or graphics.

[0080]

The dimensions of the structural elements included in the overlays of the various embodiments of the invention are essentially determined by the technology used to form the sheets and to treat the surfaces, and to the intended application, although the pitch of the grooves or lenticular elements is preferably made small enough to eliminate perception of the grooves or lenticular elements, and/or Moiré patterns resulting from parallel arrangement of light transmitting and diffusing surfaces. A pitch of less than ten grooves or elements per inch, and preferably less than twenty grooves per inch, will provide the best appearance most applications, although the invention is not in principle limited to particular sheet dimensions or pitches.

[0081]

Having thus described a number of preferred embodiments of the invention in sufficient detail to enable those skilled in the art to make and use the invention, it will nevertheless be appreciated that numerous variations and modifications of the illustrated embodiment may be made without departing from the spirit of the invention. For example, the illustrated microprism and lenticular sheet configurations are hardly exhaustive of all of the possible configurations for such sheets. Accordingly, it is intended that the invention not be limited by the above description or accompanying drawings, but that it be defined solely in accordance with the appended claims.